...these programs seem to be the only solution to help EVs go beyond their limited range.

P.S. If you can't afford a Tesla S and your driving needs require more than 50 miles one way, or thereabouts, a pure EV is probably not your solution today. That's why there are plug-in hybrids here and coming, which allow pure EV mode for much of our shorter trips. As Volt drivers have proven, real world gasoline use is drastically reduced even with a pure EV range of only 35 miles.

Also, if Envia's promises prove reasonably true, I suspect that competitor cell manufacturers will very soon find comparable performance by different but similar means. Alternately this technology could be licensed. So this could be big enough until the next "perfect battery" is realized practically.

1) You are swapping out a very expensive part of the vehicle, and they degrade. Would you be happy swapping out your brand new $10,000 battery for one with half the capacity? On the other hand, if your mechanic told you you'd need a new $10,000 battery in a few months, would you pay it if your alternative would be to just 'swap it out' for $50 and saddle someone else with the replacement costs?

2) Batteries are physically big and heavy. Many city gas stations won't want to pay for the real estate/storage facilities required.

3) Batteries are hard to change. The Leaf battery weighs almost 700 pounds, and the machinery/fixturing to handle that kind of weight is not simple or cheap.

4) Li-ion batteries do not last long if stored fully charged, so you'd reduce the overall life of the pack by storing fully charged batteries. (And if you're not storing them fully charged you lose most of the usefulness of the battery swap station.)

However, there are still safety issues and external power input needs that would need to be resolved. And cars like the Leaf are not rated for towing, though that could probably be amended if the battery trailers could weigh within 500 lbs or so.

...they prefer to discharge no more than to 30%, and not charge to more than 80%.

That's the principle with the Volt's pack, and I and many other LEAF drivers try to do that with our cars too. I even try to do that with all my lithium portable devices. Downside is that you're paying for and lugging around twice the battery you use. Anyway, the CHAdeMO fast chargers (eg, Blink) do not allow fast charging past 80%.

BTW, many in the LEAF community believe there was a large lobbying effort toward this new SAE standard largely to orphan manufacturers like Nissan that had already settled on an incompatible standard.

Thanks Beth. Of course larger vehicles may have room for multiple secondary batteries for swapping. I can also imagine a trunk design that could allow more secondary batteries to be loaded at the loss of cargo space, assuming weight balancing could be accommodated. If the swappable battery's cost was $2K or less, I could imagin people buying a couple to swap at home and charge whenever they get the best rate. This also helps to deal with the issue of coming home to park and not having enough KWh left to go somewhere (perhaps an emergency trip). It would be nice to have that spare battery you could swap in if you needed to go somewhere on short notice.

@kellerbl: I like that idea. So the swapping or second battery could be more of standard commodity so there's no worry about features/functions/condition. The primary battery could then be the platform for EV maker differentiation.

The interesting thing about the whole standard is that there is no mention of how the heat generated during charging will be handled, nor any indication of how the battery technology will change to handle the massive amount of energy dumped into the battery so very rapidly. WE could supply a thousand amp charger and probably melt most of the current batteries during a two minute "really fast charge". My point is that no mention has been made about the other end of the charging string-the battery. That is a serious issue that could use a bit of discussion.

CharlesM; Recently I have met people involved with electric transit buses. And they prefer to discharge no more than to 30%, and not charge to more than 80%. Past this range the lifetime of some battery chemistries is shortened. They prefer a sodium nickel chloride battery since it is less sensitive to charging cycles, with an operating temperature of about 300C.

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